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154 lines
4.3 KiB
ArmAsm
154 lines
4.3 KiB
ArmAsm
;
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; 2015-03-08, Greg King
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;
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; When you want to create a program with the alternate file format,
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; add "-u __BOOT__" to the cl65/ld65 command line. Then, the linker
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; will import this symbol name; and, link this module at the front
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; of your program file.
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;
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.export __BOOT__:abs = 1
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.import __RAM_START__, __RAM_SIZE__, __BSS_RUN__
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; ------------------------------------------------------------------------
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load_addr := __RAM_START__
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load_size = __BSS_RUN__ - __RAM_START__
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ram_top := __RAM_START__ + __RAM_SIZE__
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.segment "BOOT"
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; If you want to change how this bootstrap loader works, then:
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; 1. edit this assembly source code,
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; 2. define the constant ASM (uncomment the line below),
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; 3. assemble this file (and, make a listing of that assembly),
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; 4. copy the listing's hex codes into the .byte lines below (notice that most
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; of the strings are followed by CR; it's required by the OS65V monitor)
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; (be sure to match the listing's lines against the .byte lines),
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; 5. undefine ASM (recomment the line),
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; 6. assemble this file, again,
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; 7. and, add the object file to "osic1p.lib".
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;ASM = 1
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.ifdef ASM
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.include "osic1p.inc"
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.macpack generic
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load := $08 ; private variables
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count := $0A
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GETCHAR := $FFBF ; gets one character from ACIA
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FIRSTVISC = $85 ; Offset of first visible character in video RAM
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LINEDIST = $20 ; Offset in video RAM between two lines
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ldy #<$0000
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lda #<load_addr
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ldx #>load_addr
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sta load
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stx load+1
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lda #<load_size
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eor #$FF
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sta count ; store (-size - 1)
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lda #>load_size
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eor #$FF
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sta count+1
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L1: inc count ; pre-count one's-complement upwards
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bnz L2
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inc count+1
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bze L3
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L2: jsr GETCHAR ; (doesn't change .Y)
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sta (load),y
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; Show that the file is being loaded by rotating an arrow on the screen.
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;
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tya
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lsr a
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lsr a
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and #8 - 1
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ora #$10 ; eight arrow characters
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sta SCRNBASE + FIRSTVISC + 2 * LINEDIST + 11
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iny
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bnz L1
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inc load+1
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bnz L1 ; branch always
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L3: jmp load_addr
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.else
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.mac hex1 h
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.lobytes ((h) & $0F) + (((h) & $0F) > 9) * 7 + '0'
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.endmac
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.mac hex2 h
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hex1 (h) >> 4
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hex1 (h) >> 0
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.endmac
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.mac hex4 h
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hex2 >(h)
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hex2 <(h)
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.endmac
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CR = $0D
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.byte CR, CR
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.byte "." ; set an address
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hex4 ram_top ; put loader where stack will sit
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.byte "/" ; write bytes into RAM
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; ASCII-coded hexadecimal translation of the above assembly code.
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; It was copied from the assembler listing.
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.byte "A0", CR, "00", CR
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.byte "A9", CR
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hex2 <load_addr
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.byte CR, "A2", CR
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hex2 >load_addr
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.byte CR, "85", CR, "08", CR
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.byte "86", CR, "09", CR
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.byte "A9", CR
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hex2 <load_size
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.byte CR, "49", CR, "FF", CR
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.byte "85", CR, "0A", CR
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.byte "A9", CR
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hex2 >load_size
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.byte CR, "49", CR, "FF", CR
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.byte "85", CR, "0B", CR
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.byte "E6", CR, "0A", CR
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.byte "D0", CR, "04", CR
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.byte "E6", CR, "0B", CR
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.byte "F0", CR, "16", CR
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.byte "20", CR, "BF", CR, "FF", CR
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.byte "91", CR, "08", CR
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.byte "98", CR
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.byte "4A", CR
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.byte "4A", CR
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.byte "29", CR, "07", CR
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.byte "09", CR, "10", CR
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.byte "8D", CR, "D0", CR, "D0", CR
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.byte "C8", CR
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.byte "D0", CR, "E6", CR
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.byte "E6", CR, "09", CR
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.byte "D0", CR, "E2", CR
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.byte "4C", CR
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hex2 <load_addr
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.byte CR
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hex2 >load_addr
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.byte CR, "."
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hex4 ram_top
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.byte "G" ; go to address
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.endif
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